US4492922A - Magnetic sensor with two series-connected magnetoresistive elements and a bias magnet for sensing the proximity of a relatively movable magnetically permeable member - Google Patents

Magnetic sensor with two series-connected magnetoresistive elements and a bias magnet for sensing the proximity of a relatively movable magnetically permeable member Download PDF

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US4492922A
US4492922A US06/328,613 US32861381A US4492922A US 4492922 A US4492922 A US 4492922A US 32861381 A US32861381 A US 32861381A US 4492922 A US4492922 A US 4492922A
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bias
magnetoresistive elements
angle
sensor
magnetic sensor
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Hiroyuki Ohkubo
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Sony Corp
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Sony Corp
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
    • H03K17/945—Proximity switches
    • H03K17/95—Proximity switches using a magnetic detector
    • H03K17/9517—Proximity switches using a magnetic detector using galvanomagnetic devices

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  • This invention relates to a magnetic sensor and, more particularly, to a magnetoresistive-type magnetic sensor which is readily adapted to sense the proximity of a magnetically permeable member.
  • Magnetic sensors are useful in instrumentation, magnetic readers, position detectors, and various other applications.
  • the magnetic sensor is used as a so-called “contactless” switch wherein an output signal is generated, analogous to the closing or opening of a switch, when a particular magnetic event is sensed.
  • Such a contactless switch often is used in servo control systems wherein a process or machine is controlled as a function of the output of the contactless switch.
  • a semiconductive magnetic reluctance element such as a Hall effect device, has been proposed for use as a magnetic sensor.
  • the Hall effect device being a semiconductive transducer, exhibits undesirable temperature characteristics. Accordingly, when a Hall effect device is used, a temperature compensating circuit generally must be employed. Furthermore, correction and compensating circuitry also is provided, thus increasing the complexity and cost of a magnetic sensor using a Hall effect device.
  • Another magnetic sensor that has been proposed relies upon the ferromagnetic reluctance effect of a ferromagnetic metal.
  • the resistance of the ferromagnetic material changes in response to a relatively large external magnetic field in accordance with Mott's theory.
  • Mott's theory In general, as the external magnetic field increases, the resistance of the ferromagnetic material decreases. This negative relationship between the magnetic field and the resistance of the ferromagnetic material typically is linear.
  • An isotropic relationship with respect to the direction of the magnetic field obtains when the ferromagnetic material is heated to its Curie temperature. At lower temperatures, however, this isotropic relationship is minimal. Since the negative magnetic reluctance effect is useful only in the environment of relatively high magnetic fields, magnetic sensors which rely upon this effect exhibit limited utility in specialized applications.
  • Magnetic sensors employing this ferromagnetic material have been formed of an insulating substrate with a thin film of ferromagnetic material deposited thereon to form ferromagnetic strips in zig-zag or serpentine configuration. Such ferromagnetic strips exhibit magnetoresistance, whereby the resistance of the strips varies anisotropically.
  • the use of such magnetoresistive elements to detect a magnetic field is disclosed in U.S. Pat. Nos. 3,928,836, 4,021,728, 4,053,829 and 4,079,360, as well as in application Ser. Nos. 23,270, filed Mar. 23, 1979, and Ser. No. 237,115, filed Feb. 23, 1981, all assigned to the assignee of the present invention.
  • the magnetic sensor generally is comprised of two series-connected magnetoresistive elements having respective main current conducting paths which, typically, are perpendicular to each other. If a saturating bias magnetic field is supplied to both magnetoresistive elements, a predetermined output signal is produced. If the direction of the saturating magnetic field changes, the output signal will change as a function of the angle formed between the direction of the magnetic field and the main current conducting paths of the magnetoresistive elements.
  • ⁇ represents the angle of the magnetic field relative to the current conducting path. That is, the angle of the magnetic field relative to the longitudinal direction of the magnetoresistive strip which is included in the magnetoresistive element.
  • R.sub. ⁇ represents the resistance of the magnetoresistive element when the magnetic field is applied in a direction perpendicular to the direction of current flowing therethrough; and R.sub. ⁇ represents the resistance of the magnetoresistive element when the magnetic field is parallel to the direction in which the current flows therethrough.
  • NiCo nickel-cobalt
  • NiFe nickel-iron
  • NiAl nickel-aluminum
  • NiMn nickel-manganese
  • NiZn nickel-zinc alloy
  • a saturating bias field is applied to two coplanar series-connected magnetoresistive elements, and an external, movable flux source, such as a magnet, is moved with respect to the magnetic sensor.
  • the flux, or external field, generated by the magnet combines vectorially with the bias field such that the resultant field sensed by the magnetic sensor exhibits a particular angle; and this angle is detected by its action upon the magnetoresistance of the elements (as set out in equation (1) above).
  • the magnetic sensor produces an output signal which is a function of that angle and, thus, a function of the relative location of the external magnet.
  • U.S. Pat. No. 4,021,728 the direction of the bias field relative to the magnetoresistive elements is disturbed by the influence thereon of a movable, highly permeable member.
  • the output signal produced as a function of the angle of the magnetic field therethrough varies significantly with changes in temperature.
  • the bias field generally is supplied at an angle which is less than optimum. That is, relatively large changes in the angle of the resultant field through the magnetoresistive elements causes only correspondingly small changes in the output signal produced thereby. That is, the rate of change of the output signal with respect to the angle of the resultant field is relatively low.
  • such magnetic sensors do not exhibit relatively high sensitivity and low temperature-dependency, as are desired.
  • Another object of this invention is to provide an improved magnetic sensor which is readily adapted to sense the proximity of a relatively movable magnetically permeable member.
  • a further object of this invention is to provide a magnetic sensor formed of magnetoresistive elements, which sensor exhibits relatively stable temperature characteristics and, moreover, is more sensitive to changes in the direction of the magnetic field therethrough than are prior art sensors.
  • Yet another object of this invention is to provide an improved magnetic sensor, formed of magnetoresistive elements, which produces a relatively large output signal in response to relatively small changes in proximity of a magnetically permeable member which is detected thereby.
  • a magnetic sensor for sensing the proximity of a magnetically permeable member, wherein the sensor and member are relatively movable with respect to each other and have an axis of movement that is disposed within a fixed plane.
  • the sensor is comprised of two coplanar magnetoresistive elements, each element having a main current conducting path and possessing anisotropic resistance as a function of the direction of a resultant magnetic field applied thereto.
  • the magnetoresistive elements are connected in series with each other and a d. c. current is supplied thereto.
  • First and second saturating bias magnetic fields are supplied, as by a bias magnet to respective ones of the magnetoresistive elements at the same angle ⁇ o to each of the main current conducting paths in the absence of the magnetically permeable member.
  • the angle at which each bias field is supplied is changed by substantially equal and opposite small deviation angles ⁇ in response to the relative movement of the permeable member proximate the magnetic sensor.
  • An output circuit is coupled to the junction defined by the series-connected elements to produce an output signal which varies as a function of the deviation angles by which the angles of the bias fields change.
  • the angles at which the bias fields are supplied to the respective magnetoresistive elements are not identical to each other. Rather, the bias field supplied to one element exhibits an angle ⁇ o + ⁇ C to the main current conducting path therein, and the bias field supplied to the other magnetoresistive element exhibits the angle ⁇ o - ⁇ C relative to the main current conducting path therein, wherein ⁇ C is a relatively small angle with respect to the angle ⁇ o .
  • the angle of the respective bias fields relative to the main current conducting paths change by ⁇ in response to the relative movement of the magnetically permeable member.
  • FIG. 1 is a schematic diagram of a typical embodiment of a magnetic sensor which admits of substantially the same construction as that of the present invention, but which does not exhibit the improved results attained hereby;
  • FIG. 2 is a graphical representation of the relationship between the output voltage produced by the embodiment shown in FIG. 1 in response to changes in the angle of the magnetic field which is supplied to the magnetic sensor;
  • FIG. 3 is a schematic diagram of one embodiment of the present invention.
  • FIG. 4 is a graphical representation of the improved voltage/field-direction relationship attained by the present invention.
  • FIG. 5 is a schematic representation of a practical arrangement embodying the present invention.
  • FIG. 6 is a schematic diagram of another embodiment of the present invention.
  • FIG. 7 is a graphical representation of the voltage/field-direction relationship exhibited by the embodiment of FIG. 6;
  • FIG. 8 is a schematic diagram of an embodiment by which the arrangement shown in FIG. 6 is attained.
  • FIG. 9 a schematic representation of a practical arrangement embodying the invention shown in, for example, FIG. 8.
  • FIG. 1 is a schematic representation of a magnetic sensor 10 formed of magneto-resistive elements, and adapted to detect the relative proximity of a magnetically permeable member 7 which is relatively movable with respect to the magnetic sensor.
  • This magnetic sensor is comprised of an insulating substrate upon which a thin film of ferromagnetic material is deposited to form magnetoresistive elements 1 and 2 which appear as strips in zig-zag or serpentine configuration. These strips are current conductors and, as shown in FIG. 1, the main current conducting paths of magnetoresistive element 1 are disposed substantially perpendicular to the main current conducting paths of magnetoresistive element 2. Terminals 3, 4 and 5 also are formed, with terminals 3 and 4 serving to supply a d. c.
  • the main current conducting path of magnetoresistive element 1 is capable of conducting current predominantly in the vertical direction
  • the main current conducting path of magnetoresistive element 2 is capable of conducting current predominantly in the horizontal direction.
  • the magnetic sensor formed of series-connected magnetoresistive elements 1 and 2 is mounted on a bias magnet 6 which generates a bias field H sufficient to saturate the elements.
  • a bias magnet 6 which generates a bias field H sufficient to saturate the elements.
  • the bias field generated by bias magnet 6 is parallel to the main current conducting paths of magnetoresistive element 2 and, thus, perpendicular to the main current conducting paths of magnetoresistive element 1.
  • magnetically permeable member 7 is disposed within the vicinity of magnetic sensor 10, the field from bias magnet 6 will pass through member 7 and will significantly influence the net direction of the magnetic field which passes through magnetoresistive elements 1 and 2. This phenomenon is illustrated in FIG. 1 wherein member 7, such as soft iron, is proximate magnetic sensor 10.
  • the resultant bias field H B passes through magnetoresistive elements 1 and 2 in the illustrated directions.
  • magnetoresistive elements 1 and 2 are coplanar, that is, they are disposed in substantially the same plane, and the bias field H generated by bias magnet 6 is substantially parallel to this plane.
  • the bias field H B which passes through magnetoresistive element 1 undergoes a positive deviation angle ⁇ on the order of about 15°, when the permeable member 7 is disposed in the illustrated position.
  • the bias field H B which passes through magnetoresistive element 2 undergoes a deviation angle - ⁇ on the order of about 15° in response to the presence of member 7.
  • the actual deviation angle ⁇ that is, the actual angular rotation of the bias field H B through magnetoresistive elements 1 and 2 is dependent upon the proximity of member 7 to magnetic sensor 10.
  • This deviation angle ⁇ is substantially equal to zero when member 7 is relatively far from the magnetic sensor 10. That is, the deviation angle ⁇ is equal to zero when the member 7 is so far away as to be considered to be “absent". However, as the member 7 moves closer to the magnetic sensor, or as the magnetic sensor moves closer to the permeable member, the bias fields through the magnetoresistive elements are disturbed by the influence of the magnetically permeable member, thereby undergoing a deviation angle ⁇ .
  • Magnetic sensor 10 is connected in a bridge arrangement, as will now be described.
  • a suitable source of operating potential V o is coupled across d. c. current supply terminals 3 and 4 of the magnetic sensor, so as to supply d. c. current thereto.
  • Series-connected resistors 11 and 12 are coupled in parallel with series-connected magnetoresistive elements 1 and 2, as illustrated.
  • the output of operational amplifier 14 constitutes the output of the difference amplifier and, as will be described, provides a signal which varies as a function of the deviation angle ⁇ of the bias field H B . That is, the output signal produced by difference amplifier 15 varies as a function of the proximity of permeable member 7 to magnetic sensor 10.
  • the legs of the illustrated bridge arrangement are formed of resistors 11 and 12, and also the effective resistance of magnetoresistive element 1 and the effective resistance of magnetoresistive element 2.
  • the effective resistance of these magnetoresistive elements is a function of the angle between the main current conducting path therein and the direction at which the bias field is supplied thereto.
  • the voltage produced at terminal 5 has a component equal to V o /2 which, of course, is fixed, and a component which is a function of the resistance of magnetoresistive elements 1 and 2. Since the resistance of magnetoresistive elements 1 and 2 is determined by the deviation angle ⁇ , this second voltage component is a function of the deviation angle ⁇ .
  • resistors 11 and 12 function as a voltage divider to produce at terminal 13, a d. c. voltage equal to V o /2.
  • the d. c. voltage V o /2, produced at terminal 5 is cancelled by the operation of difference amplifier 15, resulting in an output voltage ⁇ V at the output of the difference amplifier, which output voltage ⁇ V may be represented as:
  • K is a constant which is a function of the anisotropic resistances R.sub. ⁇ , R.sub. ⁇ , and the gain of the difference amplifier.
  • this is the angle at which the bias field is supplied to the magnetoresistive elements.
  • Member 7 is assumed to be a magnetically permeable rod and, therefore, when the rod approaches magnetic sensor 10, the angle ⁇ rotates by the deviation angle ⁇ in response to the influence of the magnetically permeable material of rod 7 upon the bias field H.
  • the gain of difference amplifier 15 is adjusted so as to set the operating point of the illustrated embodiment to about one-third of the output level. Accordingly, a rotation of the bias field by the deviation angle ⁇ on the order of about 10° is detected and used to control further apparatus. That is, the level of the output signal produced by difference amplifier 15 in response to a 10° change in the direction of the bias field is sufficient to, for example, trigger further apparatus to operate.
  • This level change in the output signal is analogous to the closing or opening of a switch.
  • the illustrated apparatus operates as a contactless switch, effecting an operation analogous to the opening or closing of a conventional switch.
  • FIG. 2 A graphical representation of the manner in which the output signal produced by difference amplifier 15 varies as a function of the angle of the bias field through the magnetoresistive elements is illustrated in FIG. 2.
  • the broken curve of FIG. 2 represents this relationship for all angles of the bias field from 0° to 90°.
  • the bias field is supplied at an angle of 90°.
  • the angle of the bias field rotates by an amount which is determined by the proximity of member 7.
  • the 90° bias field undergoes a deviation angle ⁇ .
  • the output signal produced by difference amplifier 15 changes in a corresponding manner.
  • the magnetic sensor shown in FIG. 1, having the bias field supplied at an angle of 90° in the absence of magnetically permeable member 7, is temperature dependent.
  • the output signal produced by difference amplifier 15 exhibits a change on the order of 100-200 mV/10° C.
  • This interference in the output signal produced by the temperature dependency of magnetic sensor 10 will produce an erroneous output voltage which, in turn, will result in improper operation. That is, the contactless switch will operate even though permeable member 7 has not yet reached the point at which the bias field changes by the predetermined amount for which the magnetic sensor has been set to detect.
  • the contactless switch arrangement may operate prematurely or belatedly because of this temperature dependency of the magnetic sensor. If the magnetic sensor is intended to sense when member 7 reaches a predetermined point, this temperature dependency will interfere therewith.
  • FIG. 1 Another disadvantage of the embodiment shown in FIG. 1 is that, since the bias field is supplied (in the absence of permeable member 7) at an angle of 90°, a relatively large change in that angle results in a relatively small change in the output voltage, as clearly illustrated in FIG. 2. Stated otherwise, the magnetic sensor is not highly sensitive to changes in the bias field angle and, thus, the magnetic sensor is not highly sensitive to changes in the position of permeable member 7. Stated mathematically, in the embodiment of FIG. 1, the relationship ⁇ V/ ⁇ is too low. In accordance with the present invention, discussed below, the expression ⁇ V/ ⁇ is made desirably higher, thereby improving the detection sensitivity of the magnetic sensor; and, in addition, the output signal produced by the magnetic sensor is made less responsive to changes in temperature.
  • magnetoresistive elements 21 and 22 are schematically illustrated as having their respective current conducting paths aligned in the same direction.
  • the magnetoresistive elements are connected in series, and terminals 23 and 24 are coupled to a power supply 26 such that current flows, in series, through the current conducting paths of elements 21 and 22.
  • the junction defined by the series-connected magnetoresistive elements is coupled to an output terminal 25.
  • magnetoresistive elements 21 and 22 may be connected to additional resistors, such as resistors 11 and 12 of FIG. 1, to form a bridge arrangement, and the output of this bridge arrangement may be coupled to a difference amplifier, such as aforedescribed difference amplifier 15.
  • Magnetic sensor 20 which is formed of magnetoresistive elements 21 and 22, is supplied with a bias magnetic field H B parallel to the plane thereof, generated by a bias magnet 30 and sufficient to saturate the elements.
  • magnetic sensor 20 may be mounted on the bias magnet.
  • the magnetoresistive elements are angularly positioned such that the main current conducting paths in each exhibit the same angle ⁇ o with respect to the direction of the bias fields H B .
  • ⁇ o 45°. It will be appreciated that, if desired, other angles ⁇ o may be used; and the current conducting paths of magnetoresistive elements 21 and 22 may not necessarily be aligned in parallel with each other.
  • the proximity of member 28 to magnetic sensor 20 influences the direction at which the bias field H B is supplied to the magnetoresistive elements.
  • the presence of member 28 results in an angular rotation of the bias field supplied to magnetoresistive element 21 by the deviation angle + ⁇ ; and the presence of member 28 results in an angular rotation of the bias field supplied to magnetoresistive element 22 by the deviation angle - ⁇ .
  • the output signal derived from the magnetic sensor undergoes a corresponding change.
  • Equation (3) is seen to be equal to the Voight-Thomson equation (1), above.
  • R B the resistance of magnetoresistive element 22
  • this resistance also varies as a function of the deviation angle ⁇ in accordance with the following equation:
  • magnetoresistive elements 21 and 22 function as a voltage divider. If the voltage supplied across these magnetoresistive elements by power supply 26 is equal to V o , then the voltage produced at terminal 25 (relative to ground which is assumed to be supplied to terminal 24) may be derived as follows: ##EQU1##
  • magnetic sensor 20 is connected in a bridge arrangement similar to that shown in FIG. 1, and if this bridge is coupled to a difference amplifier, such as difference amplifier 15, then the output of the difference amplifier is a function only of the second term of equation (6), and this output signal may be represented as follows:
  • the operating point of the embodiment shown in FIG. 3 may be set at point P 1 , illustrated on the curve in FIG. 4.
  • the output signal ⁇ V derived from magnetic sensor 20 follows the solid portion of the curve in FIG. 4 until it reaches point P 1 .
  • the output signal ⁇ V is sufficient to trigger further apparatus.
  • the embodiment shown in FIG. 3 operates as a contactless switch and is actuated when the permeable member reaches the position sufficient to rotate the bias fields H B by the deviation angle ⁇ to produce the output signal corresponding to operating point P 1 .
  • FIG. 5 A practical embodiment of the arrangement shown in FIG. 3 is illustrated in FIG. 5.
  • magnetoresistive elements 21 and 22 are illustrated as elements 41 and 42, these elements constituting magnetic sensor 40 which, in turn, is mounted on bias magnet 50.
  • Elements 41 and 42 are particularly mounted such that the bias field H B is supplied at an angle of 45° (in the absence of magnetically permeable member 48) to the main current conducting paths in each element.
  • the combination of magnetic sensor 40, mounted on bias magnet 50, is received in a housing 51; and electrical connections are made to terminals 43, 44 and 45 of magnetic sensor 40 through a cable 52 which passes through a suitable aperture in the housing.
  • housing 51 also is provided with a magnetic yoke 53 whose surface is substantially parallel to the longitudinal axis of magnetically permeable member 48.
  • the use of yoke 53 serves to improve the sensitivity of the magnetic sensor to detect the approach of member 48.
  • magnetically permeable member 48 is a magnetically permeable rod.
  • the axis of movement of rod 48 relative to magnetic sensor 40 is disposed within a fixed plane. This means that, when viewed in FIG. 5, rod 48 is constrained from moving in the horizontal or vertical direction, relative to the magnetic sensor, and is movable only in the direction which is normal to the plane of the drawings.
  • rod 48 is movable in the fixed plane perpendicular to the plane of the drawings. This direction of movement is referred to as the "axis of movement”.
  • FIG. 6 Another embodiment of the present invention is illustrated in FIG. 6. It is appreciated that the FIG. 6 embodiment is similar to that shown in FIG. 3, and in an effort to avoid confusion, the elements comprising the magnetic sensor are identified with the prefix numeral "1".
  • magnetic sensor 120 is comprised of series-connected magnetoresistive elements 121 and 122, the junction defined by these series-connected elements being coupled to an output terminal 125.
  • a power supply 26 is coupled across terminals 123 and 124 to supply d. c. current to the magnetic sensor.
  • a bias magnet is provided to supply a bias magnetic field H B1 to magnetoresistive element 21 and to supply a bias magnetic field H B2 to magnetoresistive element 122.
  • the main current conducting path of magnetoresistive element 121 is disposed at an angle ( ⁇ o - ⁇ C ) with respect to the direction of bias field H B1 ; and the main current conducting path of magnetoresistive element 22 is disposed at an angle ( ⁇ o + ⁇ C ) with respect to the direction of the bias field H B2 .
  • this may be achieved by mounting magnetoresistive element 121 on the bias magnet at one angle, and by mounting magnetoresistive element 122 on the bias magnet at a different angle.
  • the angular amount ⁇ C represents the different angles at which the respective magnetoresistive elements are mounted. These angles ⁇ C are relatively small with respect to the angle ⁇ o .
  • the angle between bias field HB 1 and the current conducting path of magnetoresistive element 121 may be thought of as being slightly less than the angle ⁇ o
  • the angle between the bias field H B2 and the current conducting path of magnetoresistive element 122 may be thought of as being slightly greater than the angle ⁇ o .
  • equations (8) and (9) above are similar to aforedescribed equations (3) and (4).
  • Magnetoresistive elements 121 and 122 function as a voltage divider circuit.
  • the signal produced at output terminal 25 is an output voltage V( ⁇ ) whose magnitude varies as a function of the angle at which the respective bias fields are supplied.
  • This output voltage may be expressed as: ##EQU2## It is appreciated that magnetic sensor 120 may be connected in a bridge configuration similar to that shown in FIG. 1. Hence, the first term of equation (10) may be cancelled. As a result, the output signal derived from magnetic sensor 120 is a function only of the right-most term in equation (10), such that the output signal ⁇ V derived from the magnetic sensor may be expressed as:
  • FIG. 7 A graphical representation of equation (11) is illustrated in FIG. 7.
  • the output signal derived from magnetic sensor 120 exhibits highly stable temperature characteristics and, thus, is substantially temperature independent when the operating point P 2 is reached. This means that the sensitivity of the magnetic sensor is not deleteriously influenced by temperature changes; and the location of the magnetically permeable member at the predetermined point corresponding to operating point P 2 is detected accurately.
  • FlG. 8 is a schematic illustration of the relative alignments of the main current conducting paths of magnetic sensor 120 to achieve the respective angles ( ⁇ o - ⁇ C ) and ( ⁇ o + ⁇ C ) between these main current conducting paths and bias fields H B1 and H B2 , respectively.
  • the bias magnet (not shown) supplies the bias fields H B1 and H B2 in the same direction.
  • Magnetoresistive element 141 which corresponds to aforedescribed magnetoresistive element 121, is disposed such that the main current conducting path thereof exhibits the angle ( ⁇ o - ⁇ C ) with respect to the direction of the bias field.
  • magnetoresistive element 142 which corresponds to aforedescribed magnetoresistive element 122, has its main current conducting path at an angle ( ⁇ o + ⁇ C ) with respect to the bias field.
  • FIG. 9 A practical embodiment of the arrangement shown in FIG. 6 is illustrated in FIG. 9. It will be appreciated that the embodiment of FIG. 9 is quite similar to that described hereinabove with respect to FIG. 5 and, in the interest of brevity, further description of FIG. 9 is not provided.
  • ⁇ o 45°
  • the temperature drift of the output signal ⁇ V due to changes in temperature is substantially equal to zero.
  • temperature drift in the output signal may be reduced, and the sensitivity of the magnetic sensor may be increased even if ⁇ o is not precisely equal to 45° such as described hereinabove with respect to the embodiment shown in FIGS. 6-9. It is intended that the appended claims be interpreted as including other changes and modifications.

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US06/328,613 1980-12-09 1981-12-08 Magnetic sensor with two series-connected magnetoresistive elements and a bias magnet for sensing the proximity of a relatively movable magnetically permeable member Expired - Fee Related US4492922A (en)

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JP55-172554 1980-12-09
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JP55172553A JPS5797230A (en) 1980-12-09 1980-12-09 Magnetic sensor switch device
JP55172554A JPS5797231A (en) 1980-12-09 1980-12-09 Magnetic sensor switch device

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US5545986A (en) * 1991-06-18 1996-08-13 Mitsubishi Denki Kabushiki Kaisha Magnetic sensor having a ferromagnetic resistive element, a frame and a bias magnet integrally mounted to the frame
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US5570015A (en) * 1992-02-05 1996-10-29 Mitsubishi Denki Kabushiki Kaisha Linear positional displacement detector for detecting linear displacement of a permanent magnet as a change in direction of magnetic sensor unit
DE4341890C2 (de) * 1992-12-09 2003-11-06 Denso Corp Magnetische Detektionseinrichtung
US5637995A (en) * 1992-12-09 1997-06-10 Nippondenso Co., Ltd. Magnetic detection device having a magnet including a stepped portion for eliminating turbulence at the MR sensor
US5739752A (en) * 1993-04-26 1998-04-14 Rso Corporation, N.V. Method in detecting magnetic elements
US5644228A (en) * 1993-08-31 1997-07-01 Eastman Kodak Company Permanent magnet assembly with MR and DC compensating bias
US5705924A (en) * 1993-11-09 1998-01-06 Eastman Kodak Company Hall effect sensor for detecting an induced image magnet in a smooth material
DE19507304B4 (de) * 1994-03-02 2007-04-12 Denso Corp., Kariya Magnetfelddetektor
US5602471A (en) * 1994-03-10 1997-02-11 U.S. Philips Corporation Angle sensor including angularly spaced sensor units
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US5760580A (en) * 1994-04-26 1998-06-02 Rso Corporation N.V. Method for excitation and detection of magnetic elements by a mechanical resonance
US6018297A (en) * 1994-04-26 2000-01-25 Rso Corporation N.V. Method and device for coding electronic labels
US5969610A (en) * 1994-10-26 1999-10-19 Rso Corporation N.V. Method of detecting labels with amorphous magneto-elastical tapes
US5684397A (en) * 1994-12-07 1997-11-04 Nec Corporation Magnetoresistive sensor
US5656936A (en) * 1995-01-19 1997-08-12 Nippondenso Co., Ltd. Displacement detecting device
US5841276A (en) * 1995-05-12 1998-11-24 Nippondenso Co., Ltd Magnetic gear rotation sensor
DE19622561B4 (de) * 1995-06-07 2006-10-05 Allegro Microsystems, Inc., Worcester Halleffekt-Sensor
US6674280B1 (en) * 1999-12-31 2004-01-06 Honeywell International Inc. Position detection apparatus with distributed bridge sensor
US20040111906A1 (en) * 2001-05-22 2004-06-17 Yasunori Abe Azimuth meter
US6826842B2 (en) * 2001-05-22 2004-12-07 Hitachi Metals, Ltd. Azimuth meter
US20040160220A1 (en) * 2001-07-03 2004-08-19 Matthias Wendt Arrangement for measuring the angular position of an object
US7417421B2 (en) * 2001-07-03 2008-08-26 Nxp B.V. Arrangement for measuring the angular position of an object
US20030184305A1 (en) * 2002-04-01 2003-10-02 Nobuyoshi Niina Displacement measuring system and method
US6833706B2 (en) * 2002-04-01 2004-12-21 Schlumberger Technology Corporation Hole displacement measuring system and method using a magnetic field
US6924966B2 (en) 2002-05-29 2005-08-02 Superconductor Technologies, Inc. Spring loaded bi-stable MEMS switch
US20030223174A1 (en) * 2002-05-29 2003-12-04 Prophet Eric M. Spring loaded bi-stable MEMS switch
US20040005871A1 (en) * 2002-07-05 2004-01-08 Superconductor Technologies, Inc. RF receiver switches
WO2004006276A3 (en) * 2002-07-05 2004-12-16 Superconductor Tech Rf receiver switches
US6795697B2 (en) * 2002-07-05 2004-09-21 Superconductor Technologies, Inc. RF receiver switches
US20040017187A1 (en) * 2002-07-24 2004-01-29 Van Ostrand Kent E. Magnetoresistive linear position sensor
US20040046549A1 (en) * 2002-09-11 2004-03-11 Van Ostrand Kent E. Saturated magnetoresistive approach for linear position sensing
US6833697B2 (en) * 2002-09-11 2004-12-21 Honeywell International Inc. Saturated magnetoresistive approach for linear position sensing
US6940275B2 (en) * 2003-12-15 2005-09-06 Texas Instruments Incorporated Magnetic position sensor apparatus and method
US7023201B2 (en) * 2003-12-15 2006-04-04 Texas Instruments Incorporated Magnetic position sensor apparatus and method
US20050127902A1 (en) * 2003-12-15 2005-06-16 Sogge Dale R. Magnetic position sensor apparatus and method
US20050127903A1 (en) * 2003-12-15 2005-06-16 Sogge Dale R. Magnetic position sensor apparatus and method
US20130300408A1 (en) * 2012-05-11 2013-11-14 Memsic, Inc. Magnetometer with angled set/reset coil
US9372242B2 (en) * 2012-05-11 2016-06-21 Memsic, Inc. Magnetometer with angled set/reset coil
US20140028307A1 (en) * 2012-07-26 2014-01-30 Udo Ausserlechner Magnetoresistive sensor systems and methods having a yaw angle between premagnetization and magnetic field directions

Also Published As

Publication number Publication date
GB2089514A (en) 1982-06-23
FR2495859A1 (fr) 1982-06-11
DE3148754C2 (enrdf_load_stackoverflow) 1991-08-01
CH657949A5 (de) 1986-09-30
GB2089514B (en) 1984-10-03
CA1182171A (en) 1985-02-05
IT8125412A0 (it) 1981-12-02
IT1211140B (it) 1989-09-29
DE3148754A1 (de) 1982-08-05
FR2495859B1 (fr) 1988-03-18

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